Electronic components have become ubiquitous in modern society. The electronics industry proudly, but routinely, announces accelerated clocking and transmission speeds and smaller integrated circuit modules. While the benefits of these devices are myriad, smaller and faster electronic devices create problems. In particular, high operating frequencies inherently require fast transitions between signal levels. Fast transitions between signal levels create electromagnetic emissions throughout the electromagnetic spectrum. Such emissions are regulated by the Federal Communications Commission (FCC) and other regulatory agencies. The electromagnetic emissions radiate from a source and may impinge upon other electronic components. If the signal strength of the emissions at the impinged upon electronic component is high enough, the emissions may interfere with the operation of the impinged upon electronic component. This phenomenon is sometimes called electromagnetic interference (EMI) or crosstalk.
One way to reduce EMI is to shield the integrated circuit modules that cause EMI or that are sensitive to EMI. Typically the shield is formed of a grounded conductive material that covers a circuit module or a portion thereof. The shield may be formed during a packaging process. When electromagnetic emissions from electronic components within the shield strike the interior surface of the shield, the electromagnetic emissions are electrically shorted through the grounded conductive material, thereby reducing emissions. Likewise, when emissions from outside the shield strike the exterior surface of the shield, a similar electrical short occurs, and the electronic components do not experience the emissions.
Wafer level fan-out (WLFO) packaging technology currently attracts substantial attention in the 3D packaging area. WLFO technology is designed to provide high density input/output ports (I/O) without increasing the size of a semiconductor package. This capability allows for densely packaged small integrated circuit modules within a single wafer. As the size of the integrated circuit module is reduced, the need for isolation between various types of functional integrated circuit modules in close proximity to one another increases. Unfortunately, as the integrated circuit modules continue to become smaller from miniaturization, creating effective shields that do not materially add to the size of the integrated circuit module adds complexity and cost to the fabrication process.
As such, there is a need for an electromagnetic shield that is inexpensive to manufacture on a large scale, does not substantially change the size of the integrated circuit module, and effectively deals with interference caused by unwanted electromagnetic emissions.